The proposal concerns the central task of how infants recover individual linguistic units from continuous speech: the problem of the initial segmentation. Without segmentation, the infant cannot understand the constituents necessary to break the code. Higher aspects of syntax and semantics thus crucially depend on this segmentation, and this proposal is about the requisite perceptual capacities in the second half of the first year of life. A number of additional questions are raised, concerning the role of linguistic experience, especially "motherese." Also of interest is whether the segmentation is specific to language and whether individual differences in segmentation skill predict later language. Three complementary procedures are proposed to investigate these skills in 6-12 month old infants.